Repeated swelling and shrinking of a wood deck board can cause a finish to fail. Thompson’s says its new WaterSeal Waterproofing Stain has a flexible film that can expand and contract with the wood, reducing cracking and peeling.

In addition to having flexible elastomeric polymers, the mildew- and UV-resistant stain contains acrylic polymers that resist scuffing and marring. The stain also has two characteristics designed to speed up the job: Pigments are suspended uniformly so the can doesn’t have to be mechanically shaken before you leave the store; and the stain may be applied to damp lumber.

Stain is available in five colors, each with three opacities. Transparent stain is sold in both 1-gallon and 5-gallon containers; semi-transparent and solid versions are available in 1-gallon containers only. Prices range from $18 to $29 for a 1-gallon can; a 5-gallon container of transparent stain is about $86. The transparent stain is guaranteed for three years on horizontal surfaces; the semi-transparent version, for four years; and the solid stain, for five years.

The Thompson’s Co., 800.367.6297,